Electrical Sub Panel

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Hello, I want to install new circuits in my basement and I want to do it off of an electrical sub panel. The subs i see are only 1 phase. How to I tap into the main box? Do i still use a double pole breaker? Single pole breakers only go upto 30 amps. I want to run 4 separate circuits off the new box. Thanks.
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On Jan 30, 3:52 am, snipped-for-privacy@ptd.net wrote:

I had the same idea to power a tankless water heater but found it better for My place to upgrade to a larger,higher amp panel.. Members here might need more info as to what Your existing set-up is to give You the best help;;What amp is the main in Your box? Is the existing panel full or are there unused circuits? Are You adding 15 amp circuits? 20 amp? larger? What amp is the service from the meter outdoors? Do You have specific uses in mind for the new circuits so the amp draw can be estimated or just general use? I'm not a Sparkie but am interested after My recent upgrades.. Dean
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As Dean said, you need to furnish a lot more info. When you say that subs you see are only 1 phase, you're correct, it's rare for a residential service to have 3 phase. Are you looking to connect a machine that requires 3 phase or just not familiar with the terminology? You will need to know the size of the existing service and some idea of what's attached to it currently. You'll also need to provide details of what you're looking to connect in the basement, to determine the feeder and panel size. BTW single pole breakers do come in larger than 30 amp, however its usually more practical to build the device to operate at 240 volt and keep the amperage lower

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On Jan 30, 1:52 am, snipped-for-privacy@ptd.net wrote:

OP-
I believe you mean "legs" ..........or do you really mean phases...????
I suggest using a Square D QO Load Center..the one I'm thinking of has 8 breaker slots (100 or 125 amp rating; I think) & is feed 220V ( 2 legs) via a double pole breaker from the main.
Now you have sub panel that is mini version of your main...two legs, across which you have 220V when you use a double pole breaker.
If you really mean phases & you're trying to get 3 phase power out of a residential service you're sol unless you buy a phase converter.
but I'm pretty sure the first part of my answer will get the job done for you, since it seems like you're just looking for more amps for a heavier drawing load....and the way to get that is on a 220v circuit.
cheers Bob
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On 30 Jan 2007 01:52:21 -0800, snipped-for-privacy@ptd.net wrote:

Actually most sub panels do use 2 hot legs (240v and 120v), don't confuse that with the term, "single phase". That is really one "phase", center tapped to give you two 120v circuits. You use a 2 pole breaker in the main panel and be sure to run a 4 wire feeder to the sub. Buy the extra ground bus kit. Leave the bonding screw off the neutral bar, connected to the white wire in the fereder and it stays insulated. The bare/green wire in the feeder goes to the supplimental bar and that is where your ground wires go.
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On Tue, 30 Jan 2007 11:41:30 -0500, snipped-for-privacy@aol.com wrote:

It can be one phase or two, depending on your reference point. However, either way it's not three.

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On Tue, 30 Jan 2007 13:54:52 -0600, Mark Lloyd

This is still singe phase. The fact that it is center tapped does not add a phase. "Two phase" does exist but most people will never see it. That has the phases shifted by 90 degrees and uses 4 circuit conductors..
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On Tue, 30 Jan 2007 21:01:59 -0500, snipped-for-privacy@aol.com wrote:

Making that center tap the reference point (which seems logical since it's grounded) and examining the voltages on the other 2 conductors, you now have 2 points out of phase with other. 2 phases.
I even looked up the definition of "phase" again. Nothing about it excludes 180-degree separation.

I haven't really seen it, but have read about it.
That's definitely 2 phase. That does not limit "2 phase" to that. That would be like saying that the definition of "money" is "$15" (allowing no other amounts to qualify).
There's also 4-phase, and I have seen that but only for driving stepper motors.
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As previously posted 2 phase power is very rare now days. Typical service panels are a 3 wire single phase system. It is very common to incorrectly refer to this as "two phase". Follow the link for an explanation. http://en.wikipedia.org/wiki/Split_phase
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wrote:

Leaving out the important words that you are referring to a PARTICULAR 2-phase system.

That does SAY that, but fails to consider that the word "phase" already has a meaning.
BTW, what definition of "phase" are you using?
I'm noticing the parts of my post that you ignored.
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I suppose you can call single phase AC two phase you want but it will only tag you as an amateur around electrical professionals.
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On Wed, 31 Jan 2007 23:11:50 -0500, snipped-for-privacy@aol.com wrote:

Of course it has NOTHING to do with what I want. It has to do with what the WORD "phase" actually means.
BTW, I never said I don't call it "split phase". I just said it was 2 phase also.
Just to be sure we're still talking about the same thing, it's AC from a center-tapped transformer secondary with the center tap grounded?
Are you using a definition of "phase" that DOESN'T apply to the 120/240VAC electrical system? What it that definition?
BTW, here is one definition:
*********************************************************
3. A measure of how far some cyclic behavior, such as wave motion, has proceeded through its cycle, measured in degrees or radians. At the beginning of the phase, its value is zero; at one quarter of its cycle, its phase is 90 degrees (?/2 radians); halfway through the cycle its value is 180 degrees (? radians), and so on. ? The phase angle between two waves is a measure of their difference in phase. Two waves of the same frequency that are perfectly in phase have phase angle zero; if one wave is ahead of the other by a quarter cycle, its phase angle 90 degrees (?/2 radians); waves that are perfectly out of phase have phase angle 180 degrees (? radians), and so on. See more at wave.
**********************************************************
Source: American Heritage Science Dictionary (c) 2002
Of course it's a lot easier to understand than to explain.
AC is definitely "cyclic behavior", and when you examine the 2 nongrounded conductors at he same time you see the cycle at 2 different points. You can measure the voltage between the HOT wires of 2 different 120V outlets (120V hot to neutral). You get either 0V or 240V. That's enough to tell you something's going on.
120V is not the same as 120V (measured at different outlets). What's different about it?
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All that sounds fine, however when you are referring to residential and commercial electrical services in the US, they are generally referred to as single phase and three phase
wrote:

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On Thu, 1 Feb 2007 16:36:55 -0500, "RBM" <rbm2(remove

Yes they are. I was never arguing about that.

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wrote:

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wrote:

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On Fri, 02 Feb 2007 15:13:46 -0600, Mark Lloyd

It is just a garden variety single phase 120/240 transformer that they add a second one to and trick motors into thinking it is 3 phase. Generally they don't use the 3d transformer to make a true delta. If they wanted to spend that much money you would get 3p wye. You see it in light industrial areas where most of the load is single phase on a big 1p transformer and a second only supplies the "red" leg for the 3p load. (actually identified orange) As long as you never put L/N loads on the 208v red leg it works fine.
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wye services, but I have also seen quite a few three transformer closed delta systems. It seems to depend on the relative loads. The open delta seems to be used where the three phase load is fairly light and the closed delta where there is a heavy three phase load but 120/240 single phase service is also required. It may be a regional thing and I think the delta connection is becoming rarer and is being replaced with a separate single phase transformer where 120/240 is required.
Don Young
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Don Young wrote:

have to be derated - probably why open delta is generally light loads. Wye is easier to balance which is a good reason to use it instead of delta. (You can also get wye with 2 transformers in a Scott or T connection.)
-- bud--
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On Fri, 02 Feb 2007 20:41:33 -0500, snipped-for-privacy@aol.com wrote:

That reminds me that there's a lot about 3-phase systems that I don't know.
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